ventriloquism vs ventriloquy

ventriloquism and ventriloquy both are nouns.

Word	Noun	Adjective	Verb	Adverb
ventriloquism	Yes	No	No	No
ventriloquy	Yes	No	No	No

As nouns, ventriloquism and ventriloquy are synonyms defined as:

ventriloquism and ventriloquy: the art of projecting your voice so that it seems to come from another source (as from a ventriloquist's dummy)

ventriloquism (noun)	ventriloquy (noun)
the art of projecting your voice so that it seems to come from another source (as from a ventriloquist's dummy)	the art of projecting your voice so that it seems to come from another source (as from a ventriloquist's dummy)